remove hdb ldap create declarations

The hdb_ldap_create and hdb_ldapi_create prototypes use the "static"
keyword, but the functions themselves are not implemented as static.

Heimdal's buildsystem dynamically adds function declarations to
hdb-protos.h based on the actual function implementations. Those
declarations in hdb-protos.h are not declared as static.

Since the build system generates the declarations dynamically, just
remove them from hdb-ldap.c.

(cherry picked from commit 10519ce50d3aaa8e40bb9e1e0dee5da847648f42)
Check _kdc_db_fetch return value before dereference entry pointer

This fixes a segfault if the _kdc_db_fetch function does not find
the entry in the database (the entry pointer will be NULL if entry
is not found).

Signed-off-by: Samuel Cabrero <scabrero@zentyal.com>
Signed-off-by: Love Hörnquist Åstrand <lha@h5l.org>
Avoid kinit NPE when default cred not in keytab
Avoid appearance of if if else ambiguity

(cherry picked from commit d7c62f4f5be606e773884e994c57af2fe40fc59d)
Merge pull request #90 from ktdreyer/ldap-declaration-1-6-branch

1.6 cherry-pick: remove hdb ldap create declarations